Debt - Debt Obligations (Details) - USD ($) $ in Millions	Mar. 31, 2024	Mar. 07, 2024	Mar. 31, 2023
Debt Instrument [Line Items]
Long-term debt	$ 6,019.2		$ 6,466.6
Less: Debt discount	(13.9)		(10.4)
Less: Debt issuance costs	(5.5)		(16.3)
Net long-term debt including current maturities	5,999.8		6,439.9
Less: Current maturities	(999.4)		(1,398.2)
Net long-term debt	5,000.4		5,041.7
Senior Indebtedness
Debt Instrument [Line Items]
Long-term debt	5,309.0		5,700.0
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	0.0		100.0
Less: Debt issuance costs	$ 0.0		(8.6)
Senior Indebtedness | 4.333% 2023 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	4.333%
Effective Interest Rate	4.70%
Long-term debt	$ 0.0		1,000.0
Less: Debt discount	0.0		(0.2)
Less: Debt issuance costs	$ 0.0		(0.4)
Senior Indebtedness | 2.670% 2023 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	2.67%
Effective Interest Rate	2.80%
Long-term debt	$ 0.0		1,000.0
Less: Debt discount	0.0		(0.4)
Less: Debt issuance costs	$ 0.0		(0.2)
Senior Indebtedness | 0.972% 2024 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	0.972%
Effective Interest Rate	1.10%
Long-term debt	$ 0.0		1,400.0
Less: Debt discount	0.0		(1.2)
Less: Debt issuance costs	$ 0.0		(0.6)
Senior Indebtedness | 0.983% 2024 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	0.983%
Effective Interest Rate	1.10%
Long-term debt	$ 1,000.0		1,000.0
Less: Debt discount	(0.4)		(1.3)
Less: Debt issuance costs	$ (0.2)		(0.8)
Senior Indebtedness | 4.250% 2025 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	4.25%
Effective Interest Rate	4.60%
Long-term debt	$ 1,200.0		1,200.0
Less: Debt discount	(4.4)		(7.3)
Less: Debt issuance costs	$ (0.6)		(0.9)
Senior Indebtedness | 5.050% 2029 Notes
Debt Instrument [Line Items]
Coupon Interest Rate	5.05%
Effective Interest Rate	5.20%
Long-term debt	$ 1,000.0		0.0
Less: Debt discount	(5.2)	$ (5.3)	0.0
Less: Debt issuance costs	(2.2)		0.0
Convertible Debt
Debt Instrument [Line Items]
Long-term debt	$ 710.2		766.6
Senior Subordinated Convertible Debt | 2015 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	1.625%
Effective Interest Rate	1.80%
Long-term debt	$ 6.7		12.4
Senior Subordinated Convertible Debt | 2017 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	1.625%
Effective Interest Rate	1.80%
Long-term debt	$ 38.0		82.2
Less: Debt issuance costs	$ (0.1)		(0.4)
Senior Subordinated Convertible Debt | 2020 Senior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	0.125%
Effective Interest Rate	0.50%
Long-term debt	$ 665.5		665.5
Less: Debt issuance costs	$ (1.7)		(4.4)
Junior Subordinated Convertible Debt | 2017 Junior Convertible Debt
Debt Instrument [Line Items]
Coupon Interest Rate	2.25%
Effective Interest Rate	2.30%
Long-term debt	$ 0.0		6.5
Commercial Paper
Debt Instrument [Line Items]
Long-term debt	1,359.0		0.0
Less: Debt discount	(3.9)		0.0
Term Loan Facility
Debt Instrument [Line Items]
Long-term debt	750.0		0.0
Less: Debt issuance costs	$ (0.7)		$ 0.0